I have an older 843 that I ma working on. Machine runs but needs some more work. I have done quite a bit too it but still need more. Needs new carrier seals but I think I got that covered. My problem is when I go to lower the lift arms some times they come down slow but other times they drop violently! I mean like from 4' to the ground instantly. Linkage is a little stiff but does move. Manual shows an orfice #15 in hydraluic schematic on the line to the cylinders. The control valve was "rebuilt" right before I got machine. I know the guy that rebuilt the valve and trust his ability to do it right but the previous owner removed the valve to took it too t his mechanic. I am thinking he may have lost this orfice when he removed valve. Would that cause this problem? I have not pulled any lines to check for the orfice yet, trying to find what all could cause problem. Thanks for any help James.
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I'm not convinced the orifice is the issue. I thought it was to prevent cavetation, not for use as a restrictor to slow the speed of the arms.
If you aren't used to the machine, it will take time to get used to making it move slowly. I recently bought a 743 that has a fair bit of wear in the controls, one minute i'm lowering nice and slow, then it's on the ground. Check all pivot points for wear and repair as needed, see if that helps with your control.
If you aren't used to the machine, it will take time to get used to making it move slowly. I recently bought a 743 that has a fair bit of wear in the controls, one minute i'm lowering nice and slow, then it's on the ground. Check all pivot points for wear and repair as needed, see if that helps with your control.
HanSolo
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My 843 boom arms drop at a consistent speed with the peddle pressed full forward. That speed increases with heavier loads as compared to an empty bucket (common to most loaders I've operated). I would be alarmed though if there was no resistance from the boom rams and they just slammed down. I wonder if someone swopped the spools in the control block when it was being rebuilt. I've read on the forum here that those spools are machined to specific bores. Would that be a symptom of mis-matched spools?
I guess that could be possible Hans. If you lightly press on the pedal it will "drift" down but if pedal is pressed very much there is no control to descent it drops all the way instantly. I think there should be some kind of resistance to keep if from dropping that quick. very dangerous and aggravating if you need to control lowering. Tazza the linkages is worn so I may try rebuilding all of it but I still have never seen a laoder drop this quick. Any other loader or dozer I have had experience with will lower pretty fast but not drop instantly. Hans if you press your pedal all the way to lower fast how fast does the arms take to come down? On another note I need to replace the carrier seals which I have already bought. In the manual is shows an orfice on the case drain line where it goes to port block. Is that the screen everyone says needs to be replaced? Want to take care of filter/screen before I replace seals. Thanks James.
HanSolo
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I'd estimate quickest descent about 2 seconds from normal dump level (4' - 5'). I haven't loaded a dump truck with this one yet but probably 5 - 6 seconds from full boom elevation. That rate should be detailed in the loader specifications of the service manual. I'll be working on the machine this weekend and I'll try to remember to note that for you. I'm no help on the orifice - not having any experience servicing that component.
